Magnetic switching systems



April 28, 1959 J. A. RAJCHMAN 2,884,622

MAGNETIC swITcHING SYSTEMS Filed June 27, 195s 2 sheets-sheet 1 INVENTOR. JAH A. RAJnHMAN April 28, 1959 J. A. RAJCHMAN 2,884,622

MAGNETIC SWITCHING SYSTEMS Filed June 27, 1956 2 Sheets-Sheei 2 wN R5@ SQ www www 1N VEN TOR. RAJEHMAN mut NNN NNN.

QQ QQN \Qo NQQ QQO QQQ United States Patent O MAGNETIC SWITCHING SYSTEMS Jan A. Rajcllman, Princeton, NJ., assignor to Radio Corporation of America, a corporation of Delaware Application June 27, 1956, Serial No. 594,154

13 Claims. (Cl. 340-174) This invention relates to magnetic switching systems useful in controlling the transmisison of electric signals between two or more channels. The electric signals may be pulse signals or continuous signals and may represent intelligence, power, etc.

The present invention is an improvement upon magnetic systems of the type disclosed in my copending application iiled November l, 1954, Serial No. 465,842, entitled Magnetic Switching Systems. The systems described in my copending application use multi-apertured magnetic elements of substantially rectangular hysteresis loop material. Each of these elements has two or more input apertures and an output aperture. Selecting windings are linked in combinatorial fashion through the input apertures of the elements, and separate output circuits are linked to separate ones of the elements through their respective output apertures. A common winding is linked to all the elements through their output apertures. A desired element may be selected by applying a set of signals to the selecting windings. Signals applied to the common winding are then transmitted only to the output circuit of the desired element.

Such multi-apertured elements provide advantages over prior systems using single-apertured magnetic elements of rectangular hysteresis loop material. One advantage is that the transmission of alternating electric signals or alternating pulses from the common winding to a desired output circuit can be controlled for an indefinite time by a single set of signals applied concur ren-tly or sequentially in any order to the selecting windings. Certain other advantages provided by these multiapertured elements are described in an article by l. A. Rajchman and A. W. Lo, entitled The Transuxor, published in the March 1956, issue of the Proceedings of the IRE, at pages 321-332.

lt is among vthe objects of the present invention toprovide a magnetic system for controlling the transmission of electric signals which is simpler than previous systems.

Another object of the present invention is to provide improved magnetic switching systems using two-apertured magnetic elements for controlling the transmission of electric signals.

Another object of the present invention is -to provide improved magnetic switching systems using two-apertured magnetic elements.

Still another object of the present invention is to provide improved magnetic switching systems useful in codeconverting applications.

A magnetic system according to the present invention uses a plurality of twoapertured magnetic elements of rectangular hysteresis loop material. The selecting windings are linked in combinatorial fashion through the first apertures of the elements, and the separate output circuits are linked to separate ones of the elements through the respective second apertures. A common channel may be linked through the second apertures of all the elements. A desired element is selected by ap- "ice 2 plying a set of selecting signals to the selecting windings. When the desired element is selected, its output winding and the common channel are closely coupled so that signals appearing on one are transmitted to the other. Also, a setting winding may be linked to all the elements. A desired element then may be selected by applying input signals to the selecting windings of the desired element and concurrently applying a setting signal to the setting winding. The two-apertured elements are simpler to manufacture than those described in my copending application aforesaid and are more easily obtained. Also, the present invention provides improved code-converting circuits using these two-apertured magnetic elements. For exmple, an "n unit code can be converted to an m unit code.

The invention will be more fully understood from the following description when read in connection with the accompanying drawing wherein:

Fig. 1 is a schematic diagram of a two-apertured magnetic element which may be used in carrying out the present invention;

Fig. 2 is a schematic diagram of one embodiment of the invention in which each selecting winding is coupled to half the elements;

Fig. 3 is a schematic diagram of another embodiment of the invention in which each selecting winding is linked to all the magnetic elements of the system, and

Fig. 4 is a schematic diagram of a third embodiment of the invention especially useful in code-converting applications.

The two-apertured element 5 of Fig. l is a transfluXor core, more fully described in connection with Figs. 1 and 14(0) of the aforementioned article by Rajchman and Lo.

The element 5 is a disc-shaped core made from a substantially rectangular hysteresis loop magnetic material such as manganese-magnesium ferrite. The core 5 has a setting aperture 7 and an output aperture 9. The two apertures 7 and 9 of the transuxor core 5 provide three distinct legs l1, l2 and 13. The minimum cross-sectional areas of the narrow legs l2 and I3, respectively adjacent the output aperture 9, are equal to each other, and the minimum cross-sectional area of the wide leg l1 adjacent the setting aperture 7 is at least equal to the sum: of the minimum crosssectional areas of the narrow legs l2 and 13. A blocking winding 6 is linked to the core 5 through its setting aperture 7. An input winding 10 and an output winding 12 are each linked to the core 5 through its output aperture 9. A setting winding 8 may be linked to the middle leg l2 of the core 5 by threading the setting winding 8 (beginning at its terminal 8a) across the top surface of the core 5 and downwardly through its setting aperture 7, Athan across lthe bottom surface of the core 5, and upwardly through `the output aperture 9 and then back across the top surface of the core 5 to its terminal 8b The setting winding 8 may also be linked to the core 5 through only the setting aperture 7, if desired. Thus, after being threaded through the setting aperture 7, the setting winding 8 may be brought across the bottom surface of the core 5 to its terminal Sb.

The following explanation of the operation of the system is somewhat idealized. The precise ilux conditions during operation are not known; however, a suicient explanation to provide a basis for practicing the invention is afforded by the `theory tentatively advanced in the following explanation:

initially, each of the transiuxor cores S is in a blocked condition, as described in the Iaforementioned Rajc'hman and Lo article. A core 5 may be placed in its blocked condition by applying 4a signal of suitable amplitude to the blocking winding 6. In the blockedl condition, signals applied to the input winding 10 do not produce any appreciable ux changes in either one of the legs l2 or Z3. Substantially no flux change is produced because one or the other of the legs l2 and I3 is already saturated with iluX in the sense in which an input signal of either polarity tends to increase uX. Consequently, in the blocked condition substantially no output signals are produced in the output winding 12.

A core 5 can be changes from its blocked to its set condition by applying Ia setting signal to the setting winding 8. The setting signal produces a lux reversal in the path about the setting aperture 7, including the legs l2 and l1. The amount of uX actually reversed in the legs l2 and l1 is proportional to the amplitude of the setting signal. Each setting signal is assumed to have 'an amplitude greater than a threshold value at which Ia flux reversal is just initiated in the ux path about the setting aperture 7. The setting signal, however, does not reverse any ux in the outer leg Z3, no matter what its amplitude, because the ux in the leg Z3 is driven further into saturation in the direction in which it is already saturated by a previous 'blocking signal. In the set condition, signals iapplied to the input winding produce flux reversals in the legs l2 and I3 adjacent the output aperture 9. These flux reversals, in turn, produce signals in the output winding 12. The regions in which iluX is changed during the setting and the signal transmission operations are indicated by the dashed curves 13 and 14, respectively, enclosing portions indicated by diiTerent shading.

In the set condition, relations which exist lbetween the primary `and the secondary windings of a transformer also apply to the input and the output circuits 10 'and 12 of the transuXor core 5 provided account is taken of the characteristics of the material and the variability in the .amount of setting. Thus, the roles of the input and the output windings 10 and 12 can be interchanged at will, and signals applied to either of these windings can produce flux changes 'about the output aperture 9, thereby transmitting signals to the other of the windings.

A plurality N :2" of the transuxor cores 5 may lbe arranged in a switching system for controlling the transmission of signals to 27L output channels under t-he control of n input signals. In Fig. 2, an illustrative switching system 14 has eight of the cores 5 arranged for controlling the transmission of signals to eight separate output channels 15. Three binary input signals are used for controlling the signal-transmitting conditions of desired ones of the cores 5. Each of the cores 5 of Fig. 2 is shown in ycross-section (somewhat enlarged) along a line taken through a center line 2 2, as indicated in Fig. l. Three pairs 19a, 19h, and 19C of selecting coils 19 are linked to the cores 5 in 1combinatorial fashion. In the drawing, a linkage is indicated by a single-tum winding wound around the linked core section. Lack of the single-turn coupling indicates that a core is not linked. The rst pair 19a of selecting coils 19 :are respectively linked to interlaced halves of the cores 5 through their setting apertures 7. The second pair 19h of selecting coils 19 are respectively linked to interlaced quarters of the cores 5 through their setting aperture 7, and the third pair 19C of selecting coils are respectively linked to interlaced eighths of the cores 5 through their setting apertur 7. The upper terminal of each of the selecting coils 19 is connected to the positive terminal of a Supply source, indicated by a battery 20. The negative terminal of the battery 20 is connected to 'a common reference source, indicated in the drawing by the conventional ground symbol. Each of the lower terminals of the pair of selecting coils 19a is connected to the anode of a different one of a pair of control devices, such as a duotriode tube 21. The two cathodes of the tube 21 are connected to ground. The control electrodes of the tube 21 are connected respectively to input terminals 22a and 2217 which `are activated by a binary digit `designated as the 22 input signal. The 22 signal, for example, represents the third digit of a three-digit binary number. A binary 0 digit may be represented by the presence of a signal at the input terminal 22a and the absence of a signal 'at the input terminal 2212. A binary 1 digit may be represented by the presence of la signal at the input terminal 22h and the absence of a signal at the terminal 22a. The lower terminals of each of the coils of the second pair of selecting coils 19b are connected to the anode of a diierent one of a second pair of the control devices, such Ias the duo-triode tube 23. The two cathodes of the tube 23 are connected to ground. The two control grids of the tube 23 `are -connected respectively to the input terminals 24a and 24b. The input terminals 24 receive signals representing the 2l digit of the three-digit number. The lower terminals of each of the coils of the third pair of selecting coils 19C are connected to the anode of a different one of a third pair of control devices such yas a duo-triode tube 25. The two cathodes of the tube 25 are connected to ground. The two control grids of the tube 25 are -connected respectively to a third pair of input terminals 26a and 26h. The input terminals 27 receive signals representing the 20 digit of the three-digit number.

A common channel 17 is linked t0 all the cores 5 through their output apertures 9. The controlled signals may be continuous signals or pulse signals. A separate output channel 15 is linked to separate ones of the cores 5 through their output apertures 9.

A setting winding 27 is linked to the middle leg l2 of each of the cores 5 by being threaded rst through the setting apertures 7 of all the cores 5 and then 4brought back `and threaded through the output apertures 9 of all the cores 5. The setting winding 27 has one terminal 27a connected to the anode of 'a triode tube 28, and has its other terminal 27b connected to the positive terminal of a supply source such as a battery 29. The cathode of the setting tube 28 and the negative terminal of the battery 29 are each connected to ground. The setting tube 28 is operated 'by a setting signal applied to its control grid. Each of the duo-triode tubes 21, 23 and 25, `and the setting tube 28 is normally maintained in a nonconducting condition, as by a suitable bias means (not shown). Any other suitable sources may be used for supplying signals to the selecting coils 19 and the setting winding 27.

In operation, assume that initially each of the cores 5 is in its blocked condition, as by operating the selecting tubes 21, 23, and 25 without operating the setting tube 28. The cores 5 may be placed in the blocked condition by other suitable means, as described hereinafter. In the blocked condition, signals applied to the terminal 17a of the common channel 17 are not transmitted to any of the output circuits 15.

A desired one of the cores 5 can be selected by applying a setting signal to the control grid of the setting tube 28. The setting current flowing in the setting coil 27 is of suticient amplitude to change any of the cores 5, including the desired one, from its blocked to its set condition. At the same time, however, three input signals are applied respectively to the three input terminals 22, 24 and 26, to operate one side of each selecting tube 21, 23 and 25. The operated selecting tubes cause a current ow in their connected selecting coils 19. The currents ilowing in the selecting coils 19 hold the remaining ones of the cores 5 in their initial blocked condition.

For example, assume that it is desired to select the uppermost core 5 whose binary address is 000, as indicated by the -binary number immediately to the left of the cores 5. Thus, the group of input Signals corresponding to the binary number 000 is used to make each of the left-hand sides of the duo-triodes 21, 23 and 25 conducting. The resultant selecting currents Ib Ilow in each of the left-hand ones of the selecting coils 19. Note that one or more of the left-hand ones of the selecting coils 19 link all the cores 5 except the uppermost core 5. A setting signal is applied to the control grid of the setting tube 28. The resultant setting current Is in the setting coil 27 changes the uppermost core to its set condition by producing a ilux reversal in its legs l2 and I3. However, the selecting current Ib, concurrently o'wing in each of the left-hand selecting windings of the pairs 19a, 19b and 19C causes an opposing magnetizing force to be applied to each of the remaining cores 5. Thus, each of the remaining cores 5 has either zero magnetizing force or a net magnetizing force in a direction to hold any core receiving the net magnetizing force in its blocked condition. Accordingly, only ythe uppermost core 5, identified by the set of input signals 000, is selected.

Now, when input signals are applied to the common channel 17, corresponding ilux changes are produced in the legs Z2 and Z3 of the uppermost core 5. These flux changes in the uppermost core 5 produce corresponding signals in its output channel 15. Substantially no flux changes are produced in any of the other cores 5 by the signals appearing on the common channel 17. The uppermost core 5 remains in the set condition until it is returned to the blocked condition by one or more of the selecting currents Ib.

The transmission of any of Ithe different kinds of signals described in the aforementioned Rajchrnan and Lo article may be controlled in like manner. Thus, the controlled signals may be a sequence of symmetrical, alternating pulses or continuous wave signals. The controlled signals also may be asymmetrical pulses or continuous wave modulated signals.

Additional power in one of the phases of alternating signals may be delivered to the output channel of the selected core 5 by using a priming operation, as described in the Rajchman and Lo article. That is, an additional priming coil (not shown) may be linked to all the cores 5 through their output apertures 9. Each signal applied to the common channel 17 is preceded by a priming signal. The priming signal is used, for example, to reverse the flux in the path about the output laperture 9 of a selected core and does not cause any appreciable output in the output circuit of the selected core. A succeeding input signal applied to the common channel returns the flux in the path about the output aperture 9 of the selected core 5 to its set condition, and produces an output in the output channel 15.

Any one selecting current Ib is 4of sufficient amplitude to return the uppermost core 5 to its `blocked condition. Thus, if desired, the uppermost core 5 can be placed in its `blocked condition by applying a set of binary signals, for example the complements of the initial set of -binary signals, to turn on the right-hand side of one or more of the yduo-triode tubes 21, 23 and 25, thereby producing -a blocking current Ib in one or more of the right-hand selecting coils of the pairs 19a, 19h and 19e. However, the setting source 2S i-s not operated at this time if it is desired only to return the previously selected core 5 to its blocked condition. Another of the output channels 15 may be selected in a similar manner by applying the group of 'binary signals, identifying this other channel, to the three inputs 22, 24 and 26.

If desired, it is possible to have more than one of the output channels 15 selected at any one time. In such case, the selecting tubes 21, 23 and 25, and the setting tube 28, are operated concurrently. Observe, then, that if the address of the next selected channel 15 dilers in but one -binary digit from the address of a previously selected channel 15, then the previously selected core 5 is not returned to its blocked condition. The previously selected core 5 remains in its -set condition because the selecting current Ib, which ows in one of the selected coils linked to this core 5, is eectively cancelled Aby the setting current Is which flows at the same time in the setting coil 27. The setting current IS, however, does change the core designated by the currently-applied binary signals from its blocked to its set condition. Therefore, both the cores 5, that last selected and that currently selected, transmit signals to -their output channels 15 in accordance with the signals applied to the common channel 17. However, if the address of the next selected core differs by more than one binary digit from a previously selected one, then the previously selected core 5 is returned to its blocked condition by the extra selecting current Ib that is not cancelled by the Setting current Is. In certain applications, this type of operation may be desirable, `for example, in multiplexing operations where a group of channels may be receiving the transmitted signal at the same time. Thus, assume that the setting and the selecting currents are always applied concurrently. Also assume that the sets of selecting signals are cycled to represent successively higher-order numbered ones of the cores 5. In such case the output channels 15, whose addresses are O00, 001, 010, are successively selected, and the channel 000 remains selected during the selection of the channel 001. Also, the channels O00 and 001 remain selected during the selection of the channel 010. Then, when the channel 011 is selected, the rst channel O00 is blocked, and when the channel is selected, the preceding three channels 001, O10 and 011 are blocked. The selection cycles through the remaining channels, in like fashion, for input signals representing successively higher-order binary numbers. A diterent order of cycling can be achieved, if desired, by changing the cycling of the selecting signals.

If desired, all the cores can be returned to their blocked condition at any time by linking an additional restore coil through the setting aperture 7 of all of the cores 5, as described hereinafter in connection with another figure.

Another embodiment of the invention, where the selecting coils are used for performing both the setting and the blocking operations, is shown in Fig. 3. The system 30 of Fig. 3 illustratively has eight of the transluxor cores 5, any one of which may be selected by the group of three binary inputs 20-22. The three pairs of selecting coils 32a, 32h, and 32e are linked in combinatorial fashion to all the cores 5. Any one of the selecting coils 32 links half of the cores 5 in one sense, and the other half of the cores 5 in the opposite sense. However, more turns are used in linking a core 5 in the opposite sense than are used to link a core 5 in the one sense, as described hereinafter. The rst pair 32a of the selecting coils is linked through the blocking aperture 7 of all the cores 5. The left-hand coil of the rst pair 32a is linked to the lower halt of the cores 5 in one sense, and the upper half of the cores 5 in the opposite sense. The right-hand selecting coil of the rst pair 32a is linked to the upper half of the cores 5 in one sense, and the lower half of the cores 5 in the opposite sense. The second pair of selecting coils 32b is each linked to interlaced quarters of all the cores 5. Beginning at the bottom of the switch 30 the left-hand selecting coil of the pair 32h links the bottom two of the cores 5 in the opposite sense, then links the next two of the cores 5 in the one sense, etc. The right-hand selecting coil of the pair 32h links the bottom two of the cores 5 in the one sense, then links the next two of the cores 5 in the opposite sense, etc. The third pair of selecting coils 32C is linked to interlaced eighths of all the cores 5. Thus, beginning at the bottom of the switch 3h, the left-hand Selecting coil of the pair 32C links the bottom core 5 in the opposite sense, then links the next core 5 in the one sense, etc. The right-hand selecting coil of the pair 32C links the bottom core in the one sense, then links the next core in the opposite sense, etc. A restore coil 34 is linked to all the cores 5 through their blocking apertures 7. The upper terminal of each of the selecting coils 32a, 3211 and 32C, and the upper terminal of the restore coil 34 are connected to the positive terminal of a supply source indicated by a battery 36. The negative terminal of the battery 36 is connected to ground. The lower terminals of each pair of selecting coils 32a, 32b and 32C are connected to the respective anodes of a different one of the duo-triode selecting tubes 38a, 38h and 38e. All the cathodes of the selecting tubes 33a, 38b and 38C are connected to ground. The three pairs of control electrodes of the selecting tubes 38a, 33h and 38C are connected respectively to the three pairs of input terminals 46, 4l and 42. The three input signals respectively representing the three binary digits 22, 21 and 2 are applied to the input terminals 40, 4l and 42., respectively. The terminal 34b of the restore coil 34 is connected to the anode of a triode tube 43 which has its cathode connected to ground. A common channel winding 44 is linked to all the cores 5 through their output apertures 9, and has its upper terminal 44!) connected to ground. The common channel receives input signals at its lower terminal 44a. Each of the output channels 46 is linked through the output aperture 9 of a different core 5.

The one sense of linkage of a selecting coil to a core is that which generates a magnetizing force in a direction to change a core 5 to its blocked condition when a selecting current Ib (conventional) flows in the selecting coil 32. The opposite sense of linkage of a selecting coil 32 is that which generates a magnetizing force in a direction to change a core 5 to its set condition when a selecting current Ib ows in the selecting coil 32. Each selecting current Ib produces at least l/ n times the magnetizing force required to change a core 5 to its set condition, where n is equal to the number of binary inputs of the switch. Actually, each of the selecting currents Ib can be of suicient amplitude to change a core 5 to its set condition in the absence of any opposing magnetizing force. When a core 5 is selected, a selecting current Ib flows in each of its three oppositely-wound selecting coils and these three currents generate suicient magnetizing force to change the core to its set condition. The number of turns of a selecting coil 32, wound in the opposite sense (the set direction), may be equal to a number K which generates a magnetizing force (KI-D) equal to the minimum magnetizing force required to produce a ux reversal about the setting aperture 7 of a core 5. The number of turns of a selecting coil wound in the one sense (the blocking direction) is equal to K(n-l) where n is equal to the number of binary inputs. The current Ib flowing in a selecting coil 32, wound in the blocking direction, always generates sufcient magnetizing force to hold a core 5 to its blocked condition. Also, when the restore tube 43 is operated by a suitable restore signal, a restore current Ir flows in the restore coil 34 and produces suflicient magnetizing force to change all of the cores 5 from their set to their blocked condition. Observe that a separate setting coil may be dispensed with in the system of Fig. 3.

In operation, each of the cores 5 is initially in a blocked condition, as by operating the restore tube 43, to produce the restore current Ir in the restore coil 34. In the blocked condition, signals applied to the common channel 44 do not produce any appreciable ux in any of the cores S, and none of the output channels 46 have signals transmitted to them. A desired one of the cores 5 can be selected by applying the set of binary signals, corresponding to the address of the selected core 5, to the control grids of the selecting tubes 38u, 3817 and 38e. For example, assume that it is desired to select the uppermost core 5. In such case, signals representing the binary number 000 are applied to the selecting tubes 38 to make each left-hand side conducting. The current Ib then flows in the left-hand selecting winding of each pair32a, 32b and 32C. These three selecting currents Ib are additive, in the setting direction, in the uppermost core 5, thereby placing this core in its set condition. However, each of the remaining ones of the cores 5 receives either a zero magnetizing force or a net magnetizing force in the blocking direction. Consequently, each of the remaining cores 5 remains or is held in its blocked condition. Now, when signals are applied to the common channel 44, flux changes are produced in the uppermost core 5, and corresponding signals are transmitted to its output channel 46. After any desired time interval, another one of the cores 5 can be selected in similar fashion. Before the selection of a second one of the cores 5, the restore tube 43 is again operated to produce the restore current Ir which returns the uppermost core 5 to its blocked condition. Thus, in the system of Fig. 3, any of the cores 5 is selected one at a time for transmitting signals to their output channels 46.

Another embodiment of the invention, which may be used for converting input signals according to one code to output signals according to another code, is shown in Fig. 4. The arrangement of the system 49 of Fig. 4 is similar to that of the system of Fig. 1 except that a plurality of separate output channels, for example the four channels 50, 51, 52 and 53, are linked in a desired combinatorial fashion to the cores 5 through their output apertures 7. Also, the common channel i7 is not shown in the system of Fig. 4. However, if desired, a common channel may be linked to all the cores 5, as described for the system of Fig. l. Thus, the three input channels 20-22 are used to control the transmission of signals to the four output channels Sti-53. A desired one of the cores 5 is selected in the manner described for the system of Fig. l. Thus, when the uppermost core 5 is selected, signals applied to the common channel 17 transmit signals to the two output channels 51 and 53 linked to the uppermost core 5. Similarly, when any other of the cores 5 are selected yby a different group of inputs 20-22, signals applied to the common channel 17 are transmitted to one or more of the output channels 50-53 linked to that selected core 5. A selected core may be returned to its blocked condition, for example, by applying a set of signals to make each of the sides of the duotriodes 21 conducting. Also, a restore coil may be linked to all the cores S, as described foi the system of Fig. 3.

Observe that the system 49 of Fig. 4 may be used for producing an output on a common channel (not shown) linked to all the cores 5 when signals are applied to the output (now input) channels 50-53. The signals induced in the common channel are then representative of the algebraic sum of the signals applied to the channels 50-53 that are linked to the selected one of the cores 5. Thus, if signals are applied to the two channels 51 and 53, and if the uppermost core 5t) is selected, the resultant signal produced on the common channel represents the sum of the signals appearing on the two channels 50 and 53.

Any other known combinatorial arrangement of the output channels may be employed with each group of input signals operating to select a predetermined group of output channels. For example, in code-converting systems a system arranged similarly to the system of Fig. 4 may 'be used for converting a ve-digit code received at its input, to a seven-digit code delivered at the system output. Thus, a group of the cores S may be used to convert a conventional five-digit telegraph code to a seven-digit code. If a conventional three-out-of-ve telegraph code is used, ten of the cores 5 sutlice for conversion to the seven-unit output code. Thus, live pairs of selecting coils are linked to the ten cores so as to select the one core whose address corresponds to the complement of the ve input signals representing a character received at the inputs of the systems. Signals applied to the common channel then produce a ilux change in the one selected core. This ux change, in turn, induces a corresponding group of signals in seven of the output channels. Once the desired core is selected, the same group of signals can be repeatedly transmitted to the output channels by repeatedly applying signals to the common channel.

What is claimed is:

l. In a magnetic system, the combination comprising a plurality of magnetic cores each having only iirst and second apertures, each of said cores being of a magnetic material having a substantially rectangular hysteresis loop, a plurality of pairs of windings, said pairs of windings threading said rst apertures in accordance with a desired combinatorial code, a first signal winding threading said second apertures in each of said cores, a plurality of second signal windings, each of said second signal windings threading said second aperture of one or more of said cores, each of said cores having diierent stable response conditions including a blocked condition and a set condition, any one of said cores when in its said set condition magnetically coupling the said rst and second signal windings threaded through its second aperture, and said one core when in its said blocked condition not magnetically coupling the said rst and second signal windings threaded through its said second aperture, and means for applying a selecting signal to one of said windings in each of said pairs of windings so as to generate a net magnetizing force in a desired one of said cores, said net magnetizing force being effective when generated to change the response condition of said desired core from one of said different stable response conditions to another of said diierent stable response conditions.

2. In a magnetic system, the combination comprising a plurality of magnetic cores each having only rst and second apertures, each of said cores being of a magnetic material having a substantially rectangular hysteresis loop, a plurality of pairs of windings, said pairs of windings threading said rst apertures in accordance with a desired combinatorial code, a lirst signal winding threading said second apertures in each of said cores, a plurality of second signal windings, each of said second signal windings threading said second aperture of one or more of said cores, a setting winding, said setting winding threading said lirst apertures of said cores, each of said cores having diierent stabile response conditions including a blocked condition and a set condition and a set condition, any one of said cores when in its said set condition magnetically coupling the said first and second signal windings threaded through its second aperture, and said one core when in its said blocked condition not magnetically coupling the said irst and second signal windings threaded through its said second aperture, and means for selecting a desired one of said cores, said means including means for applying a selecting signal to one of said windings in each of said pairs of windings, and means for concurrently applying a setting signal to said setting winding, said selecting signals and said setting signal jointly operating to generate a net magnetizing force in said desired core, said net magnetizing force being effective when generated to change the response condition of said desired core from one of said diierent stable response conditions to another of said different stable response conditions.

3. In a magnetic system, the combination as claimed in claim l, wherein said means to generate a net magnetizing force in said desired core includes a setting winding, said setting winding threading both said iirst and second apertures of said cores, and means for applying a setting signal to said setting winding concurrently with the application of said selecting signals to said one winding in each of said pairs of windings, said selecting signals and said setting signal jointly operating to -generate said net magnetizing force.

4. The combination as claimed in claim l, including a restore winding, said restore winding threading said tirst apertures of said cores.

5. The combination as claimed in claim l, each of said second signal windings threading said second aperture of a different one of said cores.

6. The combination as claimed in claim 1, said second signal windings threading said second apertures in accordance with another desired combinatorial code.

7. The combination as claimed in claim l, including means for applying alternating signals to said first signal winding, said alternating signals being transmitted to said second signal winding of said desired core.

8. The combination as claimed in claim l, each of said second signal windings threading said second aperture of .a different one of said cores, and means for applying alternating signals to said second signal winding of said desired core, said alternating signals being transmitted to said rst signal winding.

9. ln a magnetic system, the combination comprising a plurality of magnetic cores each having only two apertures, each of said cores consisting of a magnetic material having a substantially rectangular hysteresis loop, a plurality of pairs of windings, said pairs of windings being threaded through a first of said apertures in said cores in accordance with a desired combinatorial code, a setting winding and a restore winding each linking Iall said cores, both said setting winding and said restore winding being threaded through said lirst aperture in each of said cores, a common channel winding, said common channel winding being threaded through a second lof said apertures in each of said cores, a plurality of output windings, each of said output windings being threaded through said second aperture of a different one of said cores, means for selecting a desired one of said cores comprising means for applying signals to one winding in each of said pairs of windings so as to generate a `magnetizing force of one polarity in each of said cores except said desired core, means for concurrently applying a signal to said setting winding so as to generate a magnetizing force of the opposite polarity in each of said cores, said `opposite-polarity magnetizing force being smaller than said one-polarity magnetizing force in all said cores except said desired core, whereby alternating signals applied to said common channel winding are transmitted to the output winding of said desired core, and means for applying a restore signal to said restore winding, said restore signal operating to generate a magnetizing force of the opposite polarity in said desired core, thereby returning said desired core to its initial condition.

l0. In a magnetic system, the combination comprising a plurality of magnetic cores each having only two apertures, each of said cores consisting of a magnetic material having a substantially rectangular hysteresis loop, a plurality of pairs of windings, said pairs of windings being threaded through a rst of said apertures in said cores in accordance with a desired combinatorial code, `a setting winding linking all said cores, said setting winding being threaded through said rst aperture in each of said cores, a common channel winding, said common channel winding being threaded through a second of said apertures in each of said cores, a plurality of output windings, said output windings being threaded through said second apertures in said cores in accordance with another combinatorial code, means for selecting a desired one of said cores comprising means for applying selecting signals to one winding in each of said pairs of windings so as to generate a magnetizing force of one polarity in each of said cores except said desired core, means for concurrently applying a setting signal to said setting winding so as to generate a magnetizing force of the opposite polarity in each of said cores, said oppositepolarity magnetizing force being substantially cancelled by said one-polarity magnetizing force in all said cores except said desired core, whereby alternating signals applied to said common channel winding are transmitted to the output windings of said desired core.

11. In a magnetic system, the combination comprising a plurality of magnetic cores each having only two apertures, each of said cores consisting of a magnetic material having a substantially rectangular hystereis loop, a plurality of pairs of windings, said pairs of windings being threaded through a first of said apertures in said cores in accordance with Ia desired combinatorial code, a setting winding linking all said cores, said setting winding being threaded through said rst aperture in each of said cores, a common channel winding, said common channel winding threading through a second aperture in each of said cores, a plurality of output windings, each of said output windings being threaded through said second aperture of a different one of said cores, and means for selecting a desired one of said cores com prising means for applying signals to one winding in each of said pairs of windings so as to generate :a magnetizing force of one polarity in each of said Vcores except said desired core, and means for concurrently applying a signal to said setting winding so as to generate a magnetizing force of the opposite polarity in each of said cores, said opposite-polarity magnetizing force being smaller than said one-polarity magnetizing force in all said cores except said desired core, whereby signals applied to said common channel winding are transmitted to the output winding of said desired core.

12. In a magnetic system, the combination comprising a plurality of magnetic cores each having two apertures, each of said cores consisting of a magnetic material having a substantially rectangular hysteresis loop, plurality of pairs of windings, said pairs of windings being threaded through a iirst of said apertures in said cores in accordance with a desired combinatorial code, a setting winding threaded through said iirst aperture in each of said cores, a common winding threaded through a second of said apertures in each of said cores, a plurality of output windings, separate ones of said output windings being threaded through said second apertures of separate ones of said cores, means for applying signals to one winding in each of said pairs, and means -for concurrently applying a signal to said setting winding, said signal applied to 4said setting winding operating to produce a substantial flux change in said desired core and being prevented from producing any substantial flux change in any of the remaining cores due to said signals applied to said winding pairs, whereby signals applied to said common channel are transmitted to the output winding of said desired core.

13. In a magnetic system, the combination comprising a plurality of magnetic cores each having two apertures, each of said cores consisting of a magnetic material having a substantially rectangular hysteresis loop, a plurality of pairs of windings, said pairs of windings being threaded through a rst of said apertures in said cores, the two windings of each pair linking different groups of said cores, one winding of any one pair being linked to a core in one sense and the other winding of a pair linking the same core in the opposite sense, a common channel winding, said common channel winding being threaded through a second of said apertures in each of said cores, a plurality of output windings, said output windings being threaded through said second aperture of separate ones of said cores, and means for selecting a desired one of said cores comprising means for applying signals to one Winding in each of said pairs, each said one winding linking said desired core in said one sense, said signals when applied being effective to produce a flux change in one sense in said desired core and to produce either no iiuX change or a flux change in the opposite sense in the remaining ones of said cores, whereby other signals applied to said common channel are transmitted to the output winding of said desired core.

References Cited in the le of this patent UNITED STATES PATENTS Chen Ian. 31, 1956 Rajchman Feb. 7, 1956 OTHER REFERENCES 

